A major topic in caries research is the influence of the uptake and distribution of fluoride and other elements in making teeth more caries resistant. In this effort, the use of glass ionomer cements which bond to enamel and dentin and release fluoride has significant potential. Studies have attempted to determine the enamel, dentin, and cementum fluoride uptake from these and other fluoride preparations by the accepted methodologies of acid etch biopsy and electrometric and chromatographic procedures. The biopsy techniques are limited in sensitivity and are not directly applicable to dentin studies, and the chromatographic procedure is time consuming and destroys the sample. Neither method can show actual distribution of elements of except to state discrete values for selected areas. The objective of this proposal is to make qualitative and quantitative studies of the content and distribution of elements in mineralized dental tissues in a direct, reliable, and repeatable manner by using Electron Probe x-Ray Spectroscopy (microanalysis), and using Class V glass ionomer cement restoratives as the experimental model. This method evaluates the energy and wavelength characteristics of x-ray emitted by a specimen during scanning electron microscopy. Since these characteristics are unique of the elements emitting the x-rays, they provide the basis for qualitative and quantitative determinations of those elements in a sensitive and accurate way. Repeated measurements can be performed since x-ray microanalysis is non-destructive. This makes this a good method for developing standard criteria for its use in caries research. Unlike other methods, x-ray analysis can be applied to any area of enamel, cementum, or dentin as well as to pits, grooves and carious areas, thus making this an important investigative method in root caries research. This study will use energy dispersive and wavelength dispersive x-ray microanalysis to produce new knowledge of the qualitative and quantitative characteristics of mineralized dental tissue uptake and distribution of fluoride and other elements from glass ionomer cements. Techniques for x-ray intensity mapping and computer image analysis will yield new data on the actual distribution of elements. These studies will provide significant new information on the content and distribution of fluoride and other elements in the study of caries prevalence and prevention.